An on-membrane quantitative analysis system for glycyrrhizin in licorice roots and traditional Chinese medicines.

An on-membrane quantitative analysis system has been developed for determining glycyrrhizin (GC) in licorice roots and traditional Chinese medicines. A GC standard and the extracts of licorice roots and traditional Chinese medicines were applied to a polyethersulfone (PES) membrane and were developed by acetonitrile/water/formic acid (45:55:2, by volume), then treated with a NaIO4 solution followed by bovine serum albumin (BSA), resulting in a GC-BSA conjugate on a PES membrane. Anti-GC monoclonal antibody was bound and then a second antibody labeled with peroxidase directed against the first antibody. Finally a substrate reacted with the enzyme and gave staining. The stained membrane was scanned and coloring spots were analyzed quantitatively using graphic analysis by NIH Image software, indicating at least 0.5 microg of GC was clearly detectable. GC can be analyzed quantitatively between 1.0 and 8.0 microg.